Silver halide emulsions containing water-insoluble hydrazine derivatives



Patented May 6, 1947 SILVER HALIDE 2,419,975 EMUL. ""SIONS' CONTAIN ING 'WATER-INS OLUBLE HYDRAZINE DERIVA- Robert E. Staufierand William S mith Rochester, N;'Y., 'assignors to Eastman Kodak Comf pany, Rochester, N. Y., a corporation of New J r e No Drawing. application-August 26, 1943,

1 Serial No. 500,086

Claims.

This invention relates to photographic emulsions and particularly to a method for incorporating hydrazine derivatives in anemulsion-for 1 increasing the speed or contrast, or both, of such emulsions.

In Trivelli and Smith U. S. application Serial No. 500,088, filed concurrently herewith, a method is described for increasing the speed or con- ---trast of gelatino-silver halide emulsions. method involves the incorporation of hydrazine Moiits derivatives, such as hydrazides- Or semicarbazides, in emulsions to eifect an improvement This in the sensitivity characteristics of the emulsion.

4 -swhen using the-method of the Trivelli and Smith application-ibis sometimes d-ifiicult to incorporate-sin the emulsion the hydrazine derivatives which are insoluble or substantially insoluble in water a It is, therefore, anobject of the present invention toprovide a method forincorporating watar-insoluble orsubstantiallywater-insoluble hydrazine derivatives in a gelatino-silver halide emulsion. A further object is to provide a method for increasing the speed or contrast of photo-- graphic emulsions by the use of water-insoluble or substantially water-insoluble hydrazine deriv- T atives. Other advantages will be apparent from 'th'elfollowing description of our invention.

These advantages are accomplished by dissolving the hydrazine derivatives in a substantially water-insoluble, water-permeable solvent for the hydrazine derivative and dispersing the mixture in the photographic emulsion.

O urmethod possesses ce'rtain distinct advantages among which are the following: (1) The materials are readily-mcorporate'd' in the emulsion beforefcoating.w .:(2) A certain buffering efi'ect is'established due to the distribution laws of Ma two phase system, lwhich makes possible closer w control-of the photographic characteristics. (3) Because of its-localization in a second .phase',the

hydrazine derivative may be more favorably placedas -far as----interiering reactions are concerned, notably hardening and keeping of the emulsion.

In general, our-method:consists in dissolving the hydrazine derivative of low-solubility in water, in a substantially water-insoluble, water-per- :m-eable, highboiling solvent for thehydrazine derivative and thissolution -is then dispersed in waterzxwhich may contain dispersing or wetting agents, gelatin; and other ingredients, or is diswperseddnzthegelatin?itself. The Water dispersion of the hydrazin-e solvent-phase is thenadded in the desired proportion to a suitable gelatinosilver halide emulsion andthisi's" coated on plates or on film support'and-dried.'-* l'lies'e coatings, after exposure, are proceSsedinsuitable photographic developers to produce the improved sensitivity characteristics.

The water-insoluble -'-hydra'zine* derivatives which may be empIOyed'according to"our invention include any of' the -water"-insoluble com pounds disclosed in Trivelli and Smith application Serial No. 500,088. More speici-ficallyy we have found that water-insoluble hydrazine derivatives of the following 'c'omposition are suitable for use according to our invention:

0 R- NHNHz or m en-genes s,

CH2C ONHNH:

R arylamine or aryl. R' l-alkyl or aryl.Wm. a 20. The following-compounds illustrate thewater- "insoluble hydrazine derivatives" which may be employed according to our invention:

NHzNHOONHT- l lHs 4-(c-tolyD-semicarbazide 4-(p-chlorophenyl)-semlcarbazide ""The product formed 'by th'reaction-of hydrazine hydrate (85%) with o-benzoyl benzoic acid in methanol solution,

GHCONHNH:

r CHzCQNHNHi Phenyl succinic dil ydrazide (I1) CsHn- CHO ONHNH:

, HiQQNHlN N11: 3 v n-Arnylsuccinicdihydrazide 7 The water-insoluble, Water+permeable solvent 1 for the hydrazine derivative may be any -'of the 'i h-igh Iboiling crystalloidal materials described in Jelley and Vittum U. S. Patent 2,322,027; :grant 'ed :Jun'e 15, 1943. These compounds are-genert'a'lly liquid at:ordinary temperatures 'or-lowmelt ing' solids. :They should have a high solvent action for the hydrazine derivative and should, of course, "be inert toward the silver-halide -emu1- sion which they areincorporated; "They 55 should be substantially colorless and stable toward light, heat and moisture in addition to being inert to the various processing baths which may be encountered, such as developers, silver removal baths, and fixing baths. They should be permeable to water and the photographic processing baths. They should be of low volatility and, in general, compounds which have boiling points above 175 C. at atmospheric pressure are suitable. They should have a sufficiently low refractive index so that the solutions of hydrazine derivatives in them have approximately the same refractive index as gelatin. They should be easily dispersible in emulsions and should be chemically inert toward the hydrazine derivatives.

The following water-insoluble, water-permeable solvents for the hydrazine derivatives have been found suitable for use in our invention, this list being illustrative only:

Phosphoric acid esters:

Tri-o-cresyl phosphate Tri-m-cresyl phosphate Phthalic acid esters:

Di-n-butyl phthalate Methyl phthalate Ethyl phthalate ,B-Methoxy ethyl phthalate B-n-Butoxy ethyl phthalate n-Amyl phthalate Other esters:

Guaiacol acetate Ethyl benzyl malonate n-Hexyl benzoate n-Butyl-o-methoxy benzoate Ethyl sebacate Miscellaneous compounds:

N-n-amyl phthalimide Ethyl-N,N-di-n-butyl carbamate It is sometimes desirable to employ a mixture of solvents in the same dispersion in order to obtain the desired combination of properties. For example, a solvent having exceptionally good solvent action might be used in combination with another solvent in the correct proportions to give the final dispersion the desired refractive index. Solvents should not be used which have adverse action on the emulsions such as desensitizing action. In certain cases a solvent which desensitizes when used alone may be employed in combination with another solvent to produce a mixture which does not have adverse desensitizing action on the emulsion.

In dispersing the mixture of hydrazine derivative and solvent in the aqueous solution, it is desirable to use an emulsifying agent such as Gardinol (a higher fatty alcohol sulfate), Arctic Syntax T (U. S. Patent 1,932,180), or Alkanol 1B. Gelatin may also be used as an emulsifying agent or the mixture of hydrazine derivative and solvent may be dispersed directly in the photographic emulsion.

The following example illustrates a suitable method for incorporating a substantially waterinsoluble hydrazine derivative in an emulsion according to our invention:

grams of 4-(o-tolyl) -semicarbazide were dissolved at 40 C. in 100 grams of methyl phthalate. This solution was then dispersed in a solution composed of 125 cc. gelatin, 21 cc. 10% Alkanol B, and 5 cc. of water were added to adjust the final gelatin concentration to 1.0%. To facilitate dispersion, the material was passed five times through a colloid mill with the rotor operating at 10,000 peripheral feet per minute and a Hydroquinone grams 45 Sodium hydroxide do 37.5 Sodium sulfite (desiccated) do Potassium bromide do 30 Water to liter 1 The plates were then rinsed in an acetic acid stop bath and fixed. When various amounts of dispersion of 4-(o-tolyl) -semicarbazlde were added to the emulsion, the speed and contrast of the emulsion were increased as shown in the following table:

ig Gamma Fog Control 13.8 4.9 .05 200 cc. emulsion 5 cc. semicarbazidc dispersion 17.9 6.6 .05 200 cc. emulsion 10 cc. semicarbazide dispersion 18.5 7.6 .05 200 cc. emulsion 40 cc. semicarbnzide dispersion 23.9 7.6 .06

The developing solution described above has a pH of 12.8. With developing solutions of lower pH, the improved speed or contrast characteristics may be obtained by the use of a lower sulfite concentration as described in the Trivelli and Smith application Serial No. 500,088.

An important criterion in the incorporation of the water-insoluble hydrazine in the emulsion is the distribution coefficient of the hydrazine between the water-insoluble solvent and. water. Hydrazine derivatives of low solubility in water and high solubility in the organic solvent produce the best dispersions. Thus, high molecular weight water-insoluble hydrazine derivatives are the compounds which are most useful.

We believe that the chief advantages of our invention are obtained during preparation and storage of the photographic emulsion. While the improved speed and contrast characteristics are obtained upon development of the emulsion, the advantages of our method of incorporating the water-insoluble hydrazine derivatives in the emulsion are apparent mainly upon preparation and storage of the emulsion. We believe that, upon development of the emulsion, the hydrazine derivatives pass into the gelatin from the organic solvent, due to the action of the alkali in the developer. In the gelatin they exert an action on the silver halide grains during development which brings about an increase in speed or contrast characteristics. It is to be understood that this statement of theory is presented only to explain the apparent action of our compounds and not to limit the scope of our invention in any way.

It will be understood that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

I. A gelatino-silver-halide emulsion capable of exhibiting improved speed and contrast characteristics when exposed and developed in a developing solution having a pH of at least approximately 9.5, comprising a gelatino-silver halide emulsion layer having uniformly dispersed therein a mixture of a substantially water-insoluble hydrazine derivative having a formula selected from the class consisting of where R is selected from the class consisting of aryl and arylamine radicals and R is selected from the class consisting of alkyl and aryl radiand cals, and a substantially water-insoluble organic where R is selected from the class consisting of aryl and arylamine radicals and R is selected from the class consisting of alkyl and aryl radicals and a substantially water-insoluble phthalic acid ester solvent for said hydrazine derivative, said ester having a boiling point above about 175 C. and being permeable to photographic processing solutions.

3. A gelatino-silver-halide emulsion capable of exhibiting improved speed and contrast characteristics when exposed and developed in a developing solution having a pH of at least approximately 9.5, comprising a gelatino-silver-halide emulsion layer having uniformly dispersed therein a mixture of a substantially water-insoluble 4-aryl semicarbazide and a substantially water-insoluble organic solvent for said semicarbazide, said solvent having a boiling point and above about C. and being permeable to photographic processing solutions.

4. A gelatino-silver-halide emulsion capable of exhibiting improved speed and contrast characteristics when exposed and developed in a developing solution having a pH of at least approximately 9.5, comprising a gelatino-silver-halide emulsion layer having uniformly dispersed therein a mixture of 4-(o-tolyl)-semicarbazide in a, substantially water-insouble organic solvent for said semicarbazide, said solvent having a boiling point above about 175 C. and being permeable to photographic processing solutions.

5. A gelatino-silver-halide emulsion capable of exhibitin improved speed and contrast characteristics when exposed and developed in developing solution having a pH of at least approximately 9.5, comprising a gelatino-silver-halide emulsion layer having uniformly dispersed therein a mixture of 4-(o-tolyl)-semicarbazide and methyl phthalate.

ROBERT E. STAUFFER. WILLIAM F. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 956,567 Caldwell May 3 1910 1,560,240 Jelley Nov. 3, 1925 2,311,098 Swan et al. Feb. 16, 1943 2,322,027 Jelley et al. June 15, 1948 1,763,990 Sheppard June 1'7, 1930 2,127,573 Sheppard et a1 Aug. 23, 1938 2,245,236 Trivelli et al. June 10, 1941 2,266,442 Schinzel Dec. 16, 1941 2,276,254 Schinzel Mar. 10, 1942 2,309,492 Albets et al. Jan. 26, 1943 FOREIGN PATENTS Number Country Date 545,444 British May 27, 1942 

